This invention relates generally to Electrically Controlled Pneumatic (xe2x80x9cECPxe2x80x9d) freight train braking systems, and more particularly, to a braking system for a locomotive consist wherein braking on non-ECP equipped trailing locomotives can be controlled from an ECP equipped lead locomotive in a manner relative to the braking being applied to ECP freight cars. Early applications of new ECP brake systems have been applied as overlays to conventional pneumatic brake systems. As an overlay, applications of ECP car brakes do not apply ECP braking action on all locomotives of a consist. Conventional locomotive air brake systems initiate a brake application on the locomotive anytime a train brake application is made. However, it is typical for the engineer to manually xe2x80x9cbail,xe2x80x9d i.e. release, the locomotive brake cylinder pressure to prevent run-in of the cars, which occurs because the cars tend to brake at a slower rate than the locomotives. However, in ECP brake systems, brake applications on each rail car occur at the same time, thus substantially reducing the xe2x80x9crun-inxe2x80x9d problem. Therefore, it would be acceptable in ECP braking to provide braking performance on the individual locomotives of a consist in the same manner as applied to the rail cars. Additionally, this would provide greater overall train braking performance, especially for short trains, without the slack action problems associated with conventional pneumatic braking.
Accordingly, there is a need for a system to provide braking effort on the full consist of locomotives in the same manner as the braking effort applied to ECP cars. Moreover, this is preferably done with only the lead locomotive of a multiple locomotive consist having to be equipped with ECP compatible head-end-unit hardware.
According to the invention, integrated locomotive braking control and ECP braking control is provided on a lead locomotive such that braking effort on non-ECP equipped trailing locomotives is applied in a manner relative to the braking effort applied on the BCP freight cars in the train. In such an integrated brake control, a data interface can be established on the lead locomotive between a head-end-unit and a brake controller. The brake controller can be a conventional xe2x80x9celectronic air brakexe2x80x9d controller. In ECP braking, the brake handle is interfaced to the electronic air brake for communicating brake commands to the head-end-unit which electrically conveys the brake commands to the ECP freight cars. In ECP braking, the electronic air brake does not reduce brake pipe pressure in response to handle positions as occurs in conventional pneumatic braking.
The integrated brake control can be programmed to provide lead locomotive brake cylinder pressure with a build-up pressure and charge rate to provide locomotive braking effort relative to the braking effort applied on the ECP freight cars. The programmable control can be implemented through a central processing unit (xe2x80x9cCPUxe2x80x9d) which can be part of the EAB or the head-end-unit. Brake pipe pressure is not altered in ECP braking such that non-ECP trailing locomotives are not braked in this manner. Therefore, to implement braking on non-ECP equipped trailing locomotives, the integrated brake control provides for the EAB on the lead locomotive to control braking on the lead locomotive via the locomotive independent brake. Conventionally, the independent brake on the lead locomotive is connected to the independent brake on trailing locomotives via a standard independent brake pneumatic connection. As a result, the independent brake on trailing locomotives is controlled from the independent brake on the lead locomotive which implements braking effort on the trailing locomotives relative to the braking effort applied on the lead locomotive and the ECP freight cars.
Other details, objects, and advantages of the invention will become apparent from the following detailed description and the accompanying drawings figures of certain embodiments thereof.